JP4936971B2 - Large electromagnetic induction heating device - Google Patents

Description

  The present invention relates to a large electromagnetic induction heating device exceeding 5 kw.

  In general, as shown in FIG. 4, the electromagnetic induction heating apparatus includes a power supply circuit 90 that converts input AC power into DC power, and an inverter circuit 93 that switches DC power to switching to high frequency power by switching elements 94 and 95. A work coil 98 that is electromagnetically induced by high-frequency power and a control circuit 99 that controls the inverter circuit 93 are provided (for example, see Patent Document 1). In this electromagnetic induction heating device, the three-phase AC power is converted into DC power by the power supply circuit 90, and the DC power is switched by the switching elements 94 and 95 of the inverter circuit 93 to be converted into high-frequency power. At this time, the switching elements 94 and 95 are driven by the control circuit 99. Then, a high-frequency current flows through the work coil 98, and an eddy current flows through a pan (not shown) due to the magnetic flux generated from the work coil 98, thereby heating the object to be heated in the pan.

Here, it is possible to manufacture a large-sized electromagnetic induction heating device exceeding 5 kW with the same circuit configuration as in FIG. However, in this large electromagnetic induction heating device, it is necessary to use components such as switching elements 94 and 95 having a large switching current. Such parts not only have a large current capacity, but also have a small amount of distribution in the market, leading to an increase in manufacturing costs. On the other hand, for example, in a 10 kW large-sized electromagnetic induction heating device, it is conceivable to use two 5 kW electromagnetic induction heating devices connected in parallel as shown in FIG.
JP 2007-66782 A

  However, as described above, when two electromagnetic induction heating devices are connected in parallel, a certain reduction in manufacturing cost can be expected, but there is a limit to the reduction in manufacturing cost. In addition, the two circuits overlap, and the entire circuit becomes large.

  The present invention has been made in view of the conventional problems, and provides a large electromagnetic induction heating device that can be manufactured at a low cost and can be reduced in size.

  The large-sized electromagnetic induction heating device of the present invention is a power supply circuit that converts input AC power into DC power, an inverter circuit that switches the DC power to a high-frequency power by switching with a switching element, and is electromagnetically induced by the high-frequency power. In a large electromagnetic induction heating apparatus comprising a work coil and a control circuit for controlling the inverter circuit, the control circuit includes one control circuit, a plurality of sets of the power supply circuit, the inverter circuit, and the work coil. Drives a plurality of the inverter circuits synchronously.

  Since the large-sized electromagnetic induction heating device of the present invention has a plurality of sets of a power supply circuit, an inverter circuit, and a work coil, it is possible to use a component having a relatively small current capacity and a large circulation amount. In addition, since one control circuit drives a plurality of inverter circuits in synchronization, the number of parts can be reduced and the circuit can be downsized. Therefore, according to the large-sized electromagnetic induction heating device of the present invention, the manufacturing cost can be reduced and the size can be reduced.

  In addition, this large electromagnetic induction heating apparatus has a coil body in which a plurality of work coils have a spiral shape, and another coil body is inserted between one coil body, so that the manufacturing cost can be reliably reduced. Realization and miniaturization are possible. That is, when the object to be heated in the pan is overheated by a plurality of work coils, the inverter circuit must be controlled in accordance with the load on the inverter circuit, so that normally a plurality of control circuits that can be driven asynchronously are required. . However, in this large electromagnetic induction heating device, since the other coil body is inserted between one coil body, the loads on the plurality of inverter circuits are almost equal, and one control circuit synchronizes the plurality of inverter circuits. Can be driven. Moreover, in this large-sized electromagnetic induction heating device, the area of the work coil that occupies the top plate portion on which the pan or the like is placed is only one work coil area, so the area of the top plate portion can be reduced. Therefore, this large electromagnetic induction heating device can surely reduce the manufacturing cost and can be miniaturized.

  Furthermore, since this large electromagnetic induction heating device is provided with current detectors that detect the input current and the output current only before and after one inverter circuit, this also reduces the manufacturing cost. The size can be reduced. As described above, the loads on the plurality of inverter circuits are almost equal, and if one control circuit drives the plurality of inverter circuits synchronously, the input currents and the output currents of the plurality of inverter circuits are almost equal. For this reason, it is sufficient to arrange a current detector only before and after one inverter circuit.

  An embodiment in which a large electromagnetic induction heating device according to the present invention is embodied in an electromagnetic induction heating stove will be described below with reference to the drawings. As shown in FIG. 1, this electromagnetic induction heating stove has a top plate pedestal 2 fixed on a main body 1, and a top plate 3 is incorporated into the top plate pedestal 2 to constitute a top plate. The top plate 3 is manufactured with a rossner board having high strength and heat resistance, and a short pan 8 is placed on the top plate 3. The front panel 4 of the main body 1 is provided with an operation display panel 5 and a fan 6 on which operation push button switches, LEDs, and the like are arranged. Further, four legs 7 that support the electromagnetic induction heating stove are fixed to the lower surface of the main body 1.

  FIG. 2 is a circuit diagram of an electromagnetic induction heating stove. This circuit is housed in the main body 1 and includes power supply circuits 10 and 30, inverter circuits 20 and 40, work coils 15 and 35, and a control circuit 50. The power supply circuits 10 and 30 have rectifying stacks 11 and 31 and smoothing capacitors 12 and 32, and convert three-phase AC power into DC power. Inverter circuits 20 and 40 convert DC power to high-frequency power by switching, and IGBTs (Insulated Gate Bipolar Transistors) 21, 22, 41, 42, flywheel diodes 23, 24, 43, 44, snubber capacitors 25, 26, 45, 46, resonance capacitors 27, 28, 47, 48 and gate drives 29, 49 for driving the IGBTs 21, 22, 41, 42. Here, the IGBTs 21, 22, 41, and 42 are “switching elements”.

  The work coils 15 and 35 are disposed below the top plate 3 in parallel with the top plate 3 and are electromagnetically induced by high frequency power. Thereby, an eddy current flows through the full-size pan 8, and the object to be heated in the full-size pan 8 is heated. Current sensors 36 and 38 are provided on the input side of the power supply circuit 30 and the output side of the inverter circuit 40, and the outputs of the current sensors 36 and 38 are input to the control circuit 50. Further, the voltage on the input side of the inverter circuit 40 is input to the control circuit 50. The control circuit 50 includes a microcomputer, a current detection circuit, a voltage detection circuit, an input / output circuit, and the like. Based on the current detected by the current sensors 36 and 38 and the voltage on the input side of the inverter circuit 40, the control circuit 50, 40 controls are performed. The control circuit 50 is connected to an operation display circuit 51 that performs input / output with an operation push button switch, an LED, and the like on the operation display panel 5. As described above, since only one set of the current sensors 36 and 38 is provided, the manufacturing cost can be reduced and the size can be reduced. Here, the current sensors 36 and 38 are “current detectors”.

  FIG. 3 is a front view of the work coils 15 and 35. The work coils 15 and 35 are composed of spiral coil bodies 15a and 35a and terminals 15b, 15c, 35b and 35c which are crimped to both ends of the coil bodies 15a and 35a. And the other coil main body 35a (15a) is inserted between one coil main body 15a (35a). The terminal 15 b is connected between the IGBT 21 and the IGBT 22, and the terminal 15 c is connected between the resonance capacitor 27 and the resonance capacitor 28. Further, the terminal 35 b is connected between the IGBT 41 and the IGBT 42, and the terminal 35 c is connected between the resonance capacitor 47 and the resonance capacitor 48.

  Next, the operation of the electromagnetic induction heating stove configured as described above will be described. First, the small pan 8 containing soup or the like is placed on the top plate 3 and a heating switch on the operation display panel 5 is pressed. The three-phase AC power is converted into DC power by the rectifying stacks 11 and 31 of the power supply circuits 10 and 30 and supplied to the inverter circuits 20 and 40 via the smoothing capacitors 12 and 32. The control circuit 50 drives the IGBTs 21 and 41 and the IGBTs 22 and 42 alternately. Thereby, the state in which current flows in the order of the IGBTs 21 and 41, the work coils 15 and 35, and the resonance capacitors 28 and 48 and the state in which current flows in the order of the resonance capacitors 27 and 47, the work coils 15, 35, and the IGBTs 22 and 42 are alternated. Repeated. As a result, a high frequency current flows through the work coils 15 and 35. And an eddy current flows into the full-size pan 8 by the magnetic flux which generate | occur | produces from the work coils 15 and 35, soup etc. in the full-size pan 8 are heated.

  Since the electromagnetic induction heating stove of this embodiment has two sets of power supply circuits 10 and 30, inverter circuits 20 and 40, and work coils 15 and 35, the rectifying stacks 11 and 31, the smoothing capacitors 12 and 32, and the IGBT 21 22, 41, 42, resonant capacitors 27, 28, 47, 48, etc., those having a relatively small current capacity and a large circulation amount can be used. In addition, since one control circuit 50 drives the two inverter circuits 20 and 40 in synchronization, the number of parts can be reduced and the circuit can be downsized. Therefore, according to the induction heating stove, the manufacturing cost can be reduced and the size can be reduced.

  In addition, in this electromagnetic induction heating stove, two sets of work coils 15 and 35 have spiral coil bodies 15a and 35a, and the other coil body 35a (15a) is interposed between one coil body 15a (35a). Is inserted, the load on the two sets of inverter circuits 20 and 40 is almost equal even if the pancake pan 8 is placed at a position shifted from the center on the top plate 3. Therefore, the input currents and the output currents of the two sets of inverter circuits 20 and 40 are almost equal, and one control circuit 50 can drive the two sets of inverter circuits 20 and 40 in synchronization. Furthermore, in this electromagnetic induction heating stove, since the area of the work coils 15 and 35 occupying the top plate portion on which the size pan 8 is placed is the area of one work coil 15 (35), the area of the top plate is reduced. be able to. Therefore, the electromagnetic induction heating stove can surely reduce the manufacturing cost and can be downsized. In this induction heating stove, the other coil body 35a (15a) is fitted between one coil body 15a (35a), but two sets of work coils 15, 35 are arranged side by side, It can also be placed on top of each other. However, in the case of arranging them side by side, the load applied to the two coils differs depending on the position on which the size pan 8 is placed, so that optimal control by one control circuit becomes difficult, and the two sets of work coils 15 depend on the position. , 35 may cause interference to reduce energy efficiency, and therefore it is better to insert the other coil body 35a (15a) between the one coil body 15a (35a). In addition, it is cooler and more compact to insert the other coil body 35a (15a) between one coil body 15a (35a) than to arrange two sets of work coils 15 and 35 one above the other. It is better in terms.

  In addition, in the electromagnetic induction heating stove of this embodiment, although a power supply circuit, an inverter circuit, and a work coil are 2 sets, 3 sets or more may be sufficient.

  The large-sized electromagnetic induction heating device of the present invention has been described above according to the embodiments. However, the present invention is not limited to these embodiments, and can be appropriately modified and applied without departing from the technical idea of the present invention. Needless to say.

  The large-sized electromagnetic induction heating device of the present invention is particularly suitable for use as a commercial kitchen device that heats a large amount of an object to be heated placed in a large size pan.

It is a perspective view of the electromagnetic induction heating stove of embodiment. It is a circuit diagram of the electromagnetic induction heating stove of embodiment. It is a front view of a work coil according to the electromagnetic induction heating stove of the embodiment. It is a circuit diagram of the conventional large-sized electromagnetic induction heating apparatus. It is a circuit diagram at the time of using and connecting two electromagnetic induction heating apparatuses in parallel regarding the conventional large-sized electromagnetic induction heating apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 30 ... Power supply circuit 15, 35 ... Work coil 15a, 35a ... Coil main body 20, 40 ... Inverter circuit 21, 22, 41, 42 ... Switching element (IGBT)
36, 38 ... current detector (current sensor)
50 ... Control circuit

Claims (2)

A power supply circuit that converts input AC power into DC power, an inverter circuit that switches the DC power to high frequency power by switching with a switching element, a work coil that is electromagnetically induced by the high frequency power, and control of the inverter circuit In a large electromagnetic induction heating device comprising a control circuit to perform,
One control circuit, and a plurality of sets of the power supply circuit, inverter circuit and work coil,
The control circuit drives a plurality of the inverter circuits synchronously ;
A plurality of the work coils have a coil body having a spiral shape, and the other coil body is inserted between the coil bodies .   The large-sized electromagnetic induction heating device according to claim 1, wherein a current detector for detecting an input current and an output current is disposed only before and after one of the inverter circuits.

Images